DE4104910C2 - Steel treatment plant - Google Patents

Description

The invention relates to a plant for metallurgical Aftertreatment of steel ladles molten steel by heating and Vacuum treatment.

In previously known ladle metallurgical plants for Heating and vacuum operation is common for each of the treatments mentioned a separate Provide treatment status, being for treatment coming ladle by means of appropriate Transport equipment (crane or transfer vehicle is brought into the respective treatment position.

The reached in the heating and vacuum system Treatment times and transportation times between Melting vessel consisting of at least one converter system or at least one electric arc furnace can, including metallurgical Post-treatment systems to the pouring equipment, for example a continuous caster, leave no one continuous casting operation. Hardly anymore cast as 1-2 melts in the so-called sequence casting will.

A longer sequence cast of ten, for example successively poured melts is only possible if the melting and treatment times in the individual units including transport times as well as required idle times less than or equal the casting time of a steel ladle in the Continuous caster is.  

For single castings or small sequences, the Continuous caster after casting has been completed for the be refitted next cast. These setup times can be up to thirty or more minutes and reduce by this operationally Downtimes productivity or Hourly output of the entire steel mill.

The object of the invention is that for a continuous steel production and achievement of longer continuous casting sequences required heating and Vacuum treatment of the liquid, but still for casting to shorten unprepared steel.

According to the invention, this object is achieved in such a way that as stated in the claims.

Due to the concentrated arrangement of the Treatment stand for two steel ladles achieved that only one heating device for heating (also called ladle furnace) and only one for evacuation Vacuum pump unit is required.

In the exemplary embodiment described below the evacuation device has two vacuum lids.

One comes to the only evacuation facility if necessary with only one vacuum lid. To do this the evacuation device, which expediently on Rail is provided movable with respect to their Track are designed so that they alternate is driven from one treatment stand to another. It should be borne in mind that the two Heating device located at treatment stations is knocked over or run over.  

The treatment facilities are swiveled away the heating device or by switching the Supply line to the vacuum pump unit alternately for heating or evacuating used.

The device of the invention can be in Install existing steelworks. Because a little The device can also take up space in plants with limited space and low Installation effort can be performed.

The main advantage of using the treatment stand according to the invention for two with molten steel filled steel ladles therein, one in prior art systems necessary transfer of the steel ladles between the Treatments heat up and evacuate too avoid, furthermore the temperature losses of the liquid Steel during treatment and transportation minimize, in the continuous caster sequential castings from perform more than two melts and the like set-up times of the continuous caster for a to use increased steel production.

The number of melts that shed in sequences are no longer operational Influencing and disturbance variables, but only from Quality program (steel analysis), including the required dimensions of the cast steel (Width × height), depending.

The course of the pan treatment at The system according to the invention comprises the following possible treatment steps:  

Phase 1: heating (ladle furnace treatment)

• - Place the pan in the treatment stand (boiler)
• - Calm down the melt
• - Slag formation and purging with inert gases
• - Sampling and temperature taking
• - Remove the warming lid
• - Swing the pan lid in Heating position
• - Warm up
• - Swinging the pan lid off
• - temperature measurement
• - Put on the warming lid

Phase 2: evacuation (vacuum treatment)

• - Retracting and lowering the vacuum lid
• - Evacuate for fore and low vacuum
• - Flooding the boiler
• - temperature and sampling
• - alloying and rinsing
• - Fine analysis correction
• - Lift the vacuum cover and drive it down
• - Lift the covered pan out of the Treatment status (boiler) and transport to Continuous caster.

The treatment steps listed here can be in o.g. Order. Single steps the treatment, such as B. rinsing, temperature measurement or Sampling, flooding the boiler etc. can be repeated or in a different order.  

The total time of a metallurgical aftertreatment is between 75 and 85 minutes, taking the treatment the melt in the ladle furnace plant in the first half and treatment in the Vacuum device in the second half of the Treatment time. With appropriate compliance the sequence time is thus ensured that Overlaps between ladle treatment (Heating) and vacuum treatment do not occur can. On the other hand, the chosen arrangement allows the Facilities and the gradual process of Heating and vacuum treatment the safe adherence to one larger number of casting sequences on the im Embodiment provided continuous casting plant.

Embodiments of the invention are as follows based on schematic principle drawings explained.

Fig. 1 shows in plan view the metallurgical post-treatment unit,

Figs. 2 in the plan view of the metallurgical after-treatment system in which both treatment stands in the operating position,

Fig. 3 shows a longitudinal section through the treatment plant and

Fig. 4 shows a cross section of the pivotably arranged heating device (ladle furnace system).

The metallurgical steel aftertreatment system shown in Fig. 1 comprises two stationary treatment stations, ie boilers ( 1 , 2 ), which essentially consist of an open container for receiving the steel ladles to be treated ( 3 , 4 ), each with a lifting - And lowerable and laterally movable vacuum lid ( 13 ) can be closed, and also a heating device arranged centrally between the two treatment stations with its liftable and lowerable pan oven lid ( 9 ) including the electrical power supply ( 7 ), ie the electrode support arm construction for the power supply and the central exhaust gas duct in the form of the flue gas suction line ( 8 ), which is arranged pivotably about a pivot point ( 12 ) and which can be brought into working position via one of the two treatment stations (stationary boilers 1 , 2 ), in the exemplary embodiment boiler ( 1 ) .

The design of the system provides that for the steel aftertreatment to be carried out in sequence, which essentially consists of heating, evacuating and degassing, including analysis adjustment by alloying and temperature adjustment, the two stationary boilers ( 1 , 2 ) up to a common shut-off device or switching element ( 18 ) are each connected to a vacuum suction line ( 17 ) and then via a central vacuum suction line ( 19 ) to only a single vacuum pump unit ( 20 ).

For the removal of the flue gases that arise when the melt is heated with the electrodes ( 9 a) of the pan lid that can be lifted and lowered ( 9 ), the swivel device ( 6 ) has a swivel joint ( 14 ) with a stationary manifold ( 15 ). connected smoke evacuation line ( 8 ) integrated.

The melt coming from a converter or an electric arc furnace is covered in the steel ladle ( 3 , 4 ) with a warming lid ( 25 ) insulated with refractory material.

For removing or putting on this warming lid ( 25 ) before or after heating the melt, in the exemplary embodiment, a track-bound, movable device ( 23 ) with a placement and removal device ( 24 ) for each treatment station (boiler 1 , 2 ) the warming lid ( 25 ) is provided.

If necessary, instead of a track-bound Device also a trackless vehicle (not shown) for handling the warming lid be used. Such a vehicle can change locations.

Fig. 1 shows the rest of the operating state in which the ladle ( 3 ) in the treatment stand (boiler 1 ) and the warming lid ( 25 ) was removed from the application and removal device ( 24 ).

Fig. 2 shows the metallurgical aftertreatment system in a further operating position, in which the ladle ( 3 ) is heated in the treatment stand (boiler 1 ) and the ladle ( 4 ) in the treatment stand (boiler 2 ) is subjected to the vacuum treatment.

Fig. 3 shows a longitudinal section through the treatment system according to Fig. 2 The ladle ( 3 ) in the boiler ( 1 ) is heated by the electrodes of the liftable and lowerable ladle furnace lid ( 9 ), while the ladle ( 4 ) shown in dashed lines in the boiler ( 2 ) is subjected to the vacuum treatment.

Fig. 4 shows a cross section of the entire heating device in the heating position. The ladle furnace lid ( 9 ) is located above the ladle ( 3 ), which was inserted into the boiler ( 1 ). The ladle furnace lid has a double circumferential edge on the underside with which it grips the upper edge of the steel ladle without contact in a labyrinthine manner. The heating device, shown here in the working position, consists of the swivel device ( 6 ) with pan oven lid ( 9 ), the lifting and lowering device for the electrodes ( 9 b) and the lifting and lowering device for the pan oven lid ( 9 c), which are in the supports the front part by means of rollers ( 11 ) on a support structure ( 10 ). The swivel device ( 6 ) can be rotated about a swivel point ( 12 ) into the respective working or waiting position. A flue gas suction line ( 8 ) is connected to the stationary collecting line ( 15 ) via a swivel joint ( 14 ). During the heating process, the flue gas socket ( 16 ) of the pan lid ( 9 ) is flush with the flue gas suction line ( 8 ).

During the steel aftertreatment, either during heating or during vacuum treatment, aggregates for slag formation and alloying agents for adjusting the final analysis of the treated, molten steel are made from a common bunker system ( 28 ) via a pivotable tube ( 26 ) via corresponding metering devices ( 27 ) admitted.

Reference list

1 stationary boiler (treatment level I)
2 stationary kettles (treatment level II)
3 steel ladle (treatment stand I)
4 steel ladle (treatment stand II)
5 transformer / transformer
6 swivel device
7 Electrical power supply
8 flue gas extraction line
9 pan oven lids
9 a electrodes
9 b Electrode lifting and lowering device
9 c Pan lid lifting and lowering device
10 support structure
11 rolls
12 pivot point
13 vacuum cover
14 swivel
15 Stationary manifold
16 flue gas spigot
17 Vacuum suction line
18 shut-off or switching element
19 Central vacuum suction line
20 vacuum pump unit
21 Vacuum lid support structure
22 lifting and lowering device
23 mobile device for warming lid
24 Laying and removal device for warming lids
25 warming lid
26 Swiveling tube
27 dosing device
28 bunker system.

Claims (3)

1. Plant for the metallurgical aftertreatment of liquid steel by heating and vacuum treatment with two stationary boilers for receiving steel ladles with a single heating device, consisting of a transformer, a swivel device with electrical power supply and a lifting and lowering device for the electrodes and a pan Oven cover with a single evacuation device and with laterally movable, liftable and lowerable vacuum covers, characterized in that a lifting and lowering device ( 9 ) with the electrical power supply ( 7 ) is arranged on the swiveling device ( 6 ) arranged between the stationary boilers ( 1 , 2 ) c) is arranged for the pan oven lid ( 9 ). 2. Installation according to claim 1, characterized in that the flue gas suction line ( 8 ) arranged on the swivel device ( 6 ) is connected at one end via a rotary joint ( 14 ) to a stationary manifold ( 15 ) and at the other end flush with the flue gas nozzle during the heating process ( 16 ) of the pan lid ( 9 ) is brought together. 3. Plant according to claim 1, characterized in that for both steel ladles ( 3 , 4 ) at least one mobile device ( 23 ) is provided, which is equipped with devices ( 24 ) for placing and removing warming lids ( 25 ).